A : Primary alcohol is prepared by the reaction of primary amine with `HNO_(2)` .
R : Dimethyl amine is a primary amine but does not form methyl alcohol with `HNO_(2)` .

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1)
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2)
C. If Assertion is true statement but Reason is false , then mark (3)
D. If both Assertion and Reason are false statements , then mark (4)

Answer

To solve the given assertion-reason question, we will analyze both the assertion (A) and the reason (R) step by step.

### Step 1: Analyze the Assertion (A)
**Assertion:** Primary alcohol is prepared by the reaction of primary amine with `HNO2`.

1. **Definition of Primary Amine:** A primary amine is an amine where the nitrogen atom is attached to one alkyl or aryl group and two hydrogen atoms.
2. **Reaction with HNO2:** When a primary amine reacts with nitrous acid (HNO2), it forms an unstable diazonium salt. This reaction typically occurs in an acidic medium (like HCl).
3. **Formation of Alcohol:** The diazonium salt can then decompose to form an alcohol. Specifically, when the diazonium salt is treated with water, it can yield the corresponding alcohol.

**Conclusion for Assertion:** The assertion is **True** because primary alcohols can indeed be prepared from primary amines using HNO2.

### Step 2: Analyze the Reason (R)
**Reason:** Dimethyl amine is a primary amine but does not form methyl alcohol with `HNO2`.

1. **Definition of Dimethyl Amine:** Dimethyl amine is actually a secondary amine because the nitrogen atom is attached to two methyl groups (–CH3) and one hydrogen atom.
2. **Reactivity with HNO2:** Secondary amines do not react with nitrous acid to form alcohols. Instead, they typically do not undergo the same reaction as primary amines do.
3. **Conclusion for Reason:** The reason is **False** because dimethyl amine is not a primary amine; it is a secondary amine, and thus it cannot form methyl alcohol through the reaction with HNO2.

### Final Conclusion
- **Assertion (A)** is **True**.
- **Reason (R)** is **False**.

### Summary
- The assertion is correct as primary alcohols can be formed from primary amines using HNO2.
- The reason is incorrect because dimethyl amine is not a primary amine; it is a secondary amine.